Graphene Sheet Manufacturing Breakthrough

Another step towards the production and use of graphene has been achieved by a team led by Oxford University scientists by finding a method to reduce defects when growing the promising material. This addresses a key problem of growing graphene by using chemical vapor deposition to form tiny flakes of the one atom-thick layer of carbon, normally leading to defects and chaotic orientation that prevent electrons from flowing freely within the material.

The scientists discovered a method to line up the graphene flakes, known as "domains," by manipulating the alignment of carbon atoms on a relatively cheap copper foil - the atomic structure of the copper surface acts as a "guide" that controls the orientation of the carbon atoms growing on top of them.

"Current methods of growing flakes of graphene often suffer from graphene domains not lining up," said Professor Nicole Grobert of Oxford University's Department of Materials who led the work. "Our discovery shows that it is possible to produce large sheets of graphene where these flakes, called 'domains', are well-aligned, which will create a neater, stronger, and more 'electron-friendly' material."

The ability to control the copper guide was the missing piece, in combination with the pressure applied during growth, in order to gain better control over the properties like the thickness of these domains, the geometry of their edges, and the grain boundaries where they meet - "seams" that act as obstacles to the smooth progress of electrons necessary to create efficient graphene-based electrical and electronic devices.

"People have used copper as a base material before, but this is the first time anyone has shown that the many different types of copper surfaces can indeed strongly control the structure of graphene," said Professor Grobert.

The researchers say that the size of the sheet of graphene that can now be created would be only limited by the size of the copper base sheet.

The Oxford-led team has shown that it is also possible using the new technique to selectively grow bilayer domains of graphene - a double layer of closely packed carbon atoms - which are of particular interest for their unusual electrical properties.

"It's an important step towards finding a way of manufacturing graphene in a controlled fashion at an industrial scale, something that is essential if we are to bridge the gap between fundamental research and building useful graphene-based technologies."